Method of improving the heat stability of polyvinyl chloride articles



Patented Sept. 15, 1942 UNITED STATES PATENT oFFlcs METHOD ,oF nuraovme rrna HEAT s'rs- BILITY OF POLYVINYL CLES ' CHLORIDE ARTI- Emil Hubert, Dessau-Ziebigk, Herbert Rein, Leipzig, and Karl Riissler, Berlin-Karlshorst, Germany; vested in the Alien Property Custodian No Drawing. Application July 6, 1939. Serial No.

283,0:18. In Germany July 6,

1 Claim. (Cl. 8-1155) polymerizates are, therefore, of only limited utility for various technical purposes and especially for the textile industry.

It is therefor an object of the invention to provide a process for improving the thermal stability of shaped articles consisting of or comprising polyvinyl chloride.

Further objects will become apparent from the detailed description following hereinafter.

The process consists in a subsequent treatment of the shaped articles with'gaseous halogen or with halogen dissolved in water or another indifferent solvent. For example, threads, loose fibers, fabrics, films, bands, hose'pipes or rods of such material may be subjected to the aftertreatment with good result. The products obtained have a considerably raised softening point, so that they are suitable for many purposes for which they were unsuitable previously.

Even articles made of polyvinyl chloride, afterchlorinated in solution as described in U. 8. Patent No. 1,982,765 may be improved in their thermal stability if the articles are after-treated in the manner indicated above with gaseous or dissolved halogen.

ti The following examples illustrate the inven- Example 1 Threads of polyvinyl chloride having 56 per cent of chlorine which begin to shrink at 70 C. are treated for 1-2 days at 40-50 C. with bromine water of 1 per cent strength. After separating the excess of bromine and drying, there is obtained a thread which begins to shrink at a temperature between 85 and 90 0., so that its stability to heatis better than that of a thread of after-chlorinated polyvinyl chloride.

Example 2 A thread of polyvinyl chloride having 66 per cent of chlorine is treated for 24 hours with moist chlorine gas at room temperature. There is obtained a thread which first begins to shrink at a temperature above 95 0., whereas the untreated polyvinyl chloride threads begin to shrink at a temperature of 70 C.

Example 3 Threads of amixed polymerizate from vinyl chloride and vinyl acetate (85:15) which in untreated condition softens at about 60 C. are exposed for 72-96 hours to an atmosphere of chlorine. After this treatment the softening point is about 80 C. and when the thread is heated to this temperature it shrinks considerably less than it did before the treatment with chlorine.

- Ezcample 4 A fabricconsisting oi the threads specified in Example 3 is treated under tension for 24-48 hours at 40-50" C. with gaseous chlorine. The

softening point is thereby raised to about C.

Example 5 An after-chlorinated polyvinyl chloride spu to thread and containing about 62'per cent of chlorine and having a softening point of 82 C. is treated with bromine water of 1 per cent strength at 40-50 C. After 12-24 hours the excess of bromine is removed, whereupon the thread is found to have a softening point of about C.

Example 6 A method of raising the softening point of artificial threads spun from polyvinyl chloride containing 56% of chlorine which consists in subjecting said threads at room temperature to the action of an atmosphere of moist gaseous chlorine for 24 hours to thereby raise the temperature at which the threads begin to shrink from 70 C. to 95 C.

mm. nonna'r. manner new. man ROSSLER. 

